Since many electric instruments are arranged around an instrument panel of a motor vehicle, and control circuit units, meters, indicator lumps and switches for controlling and monitoring these electric instruments are concentrated there, therefore the number of electric wires for constructing an instrument wiring harness increases greatly, its wiring form becomes complicated due to the increasing number of the electric wires and increasing weight thereof, resulting in that the mounting of the electric wires and connector-joining work between the harness and the electric instruments require a great deal of labor and time, making the maintenance difficult to do.
In order to solve these problems, the applicant has so far proposed measures for simplifying the wiring form of a wiring harness by making meters and relevant electric instruments be a meter module around an instrument panel.
FIG. 13 is an exploded perspective view illustrating an example of a conventional meter for use in a motor vehicle proposed by the applicant. As shown in FIG. 13, the meter for use in a motor vehicle includes a front glass 5, plate 6, dial (i.e., dial plate) 2, casing 12, board assembly 13, and stepper motor 83b as a movement. A bracket, lamp casing and housing are incorporated with the casing 12. The dial 2 is provided with meters such as a speed meter 21, tachometer 22, thermometer 23 and fuel meter 24, and meters consisting of various indicators such as a warning display 25 on a surface of the dial 2.
The speed meter 21 includes meter design part 21a consisting of the scale, characters and indices, and a through hole 21b formed at the center for attaching a pointer 83f on a front surface of the dial 2 by guiding a rotation shaft of the stepper motor 83b therethrough. Similarly, the tachometer 22 includes a meter design part 22a and through hole 22b, the thermometer 23 includes a meter design part 23a and through hole 23b, and the fuel meter 24 includes a meter design part 24a and through hole 24b. 
A translucent paint such as a white paint is printed on each of the meter design parts 21a, 22a, 23a, 24a and 25a of the speed meter 21, tachometer 22, thermometer 23, fuel meter 24 and warning display 25, respectively. A light-blocking paint such as a black paint is printed on a portion except each design part. Each design part disperses the light from a light source (not shown in the figure) attached to the board assembly 13 by means of a lamp casing of the casing 12 so as to light up from the back.
For example, the meter design part 25a of the warning display 25 is illuminated by a shell-type light-emitting diode (LED) display element (not shown in the figure) mounted on the board assembly 13 as a light source when a warning is given.
On the board assembly 13, there are mounted an IC as a drive element for driving a LED display element for the warning display 25, IC as a drive element for driving a LCD (liquid crystal display) as an assistant display element for displaying such as a trip meter, an IC as a drive element for driving a stepper motor 83b, and other electronic instruments for carrying out various functions of meters for a vehicle.
Further, as shown in FIG. 14, the stepper motor 83b includes an upper casing 83b-1 and lower casing 83b-2 made of synthetic resin or the like. A pair of engaging holes 83b-1a of the upper casing 83b-1 engages with an engaging projection 83b-2a formed on an outer wall of the lower casing 83b-2, thereby fixing the upper and lower casings 83b-1, 83b-2 to each other. A rotation shaft 83b-3 for attaching a needle (indication needle) 83f penetrates through to protrude from an upper surface of the upper casing 83b-1. A side wall of the upper casing 83b-1 is provided with an arm-shaped hook 83b-1c in the inverse direction to the rotation shaft 83b-3.
As for the meter for a vehicle, a bracket, lamp casing and housing are incorporated with the casing 12, and the board assembly 13 is assembled into a single board, thereby having advantages of easy assembling and simple structure.
FIGS. 15 and 16 show a perspective view and cross sectional view taken along B-B line illustrating another example of a conventional meter for a vehicle. As shown in FIGS. 15 and 16, the meter for a vehicle includes: a display board 101 having a circuit pattern (not shown in the figure) capable of electric conduction between a front surface 101a and back surface 101b; and a display devices such as a speed meter 102, tachometer 105, fuel meter 108 and thermometer 111, each mounted on the front surface 101a of the display board 101.
The speed meter 102 includes: a stepper motor 103 as a movement fixed to the display board 101; and a needle 104 attached to an output shaft 103a of the stepper motor 103 that functions as internal equipment for driving the needle 104 in response to measured quantity data of a speed of the vehicle.
The tachometer 105 includes a stepper motor 106 and a needle 107 attached to an output shaft 106a of the stepper motor 106 that functions as internal equipment for driving the needle 107 in response to measured quantity data of number of revolutions of an engine.
The fuel meter 108 includes a stepper motor 109 and a needle 110 attached to an output shaft 109a of the stepper motor 109 that functions as internal equipment for driving the needle 110 in response to measured quantity data of the amount of fuel.
The thermometer 111 includes a stepper motor 112 and a needle 113 attached to an output shaft 112a of the stepper motor 112 that functions as internal equipment for driving the needle 113 in response to measured quantity data of temperature in a vehicle.
Between each stepper motor and the corresponding needle, there is arranged a dial, which is provided with a scale and indices such as numbers, characters and marks on a surface on the dial (not shown in the figure).
The meter for a vehicle includes: an infrared light-receiving element 114 and an IC (Integrated Circuit) 115 for a stepper motor driver and infrared communication, each of which is mounted on the back surface 101b of the display board 101 and electrically connected to the speed meter 102 mounted on the front surface 101a; an infrared light-receiving element 116 and an IC (Integrated Circuit) 117 for a stepper motor driver and infrared communication, each of which is electrically connected to the tachometer 105 mounted on the front surface 101a; an infrared light-receiving element 118 and an IC (Integrated Circuit) 119 for a stepper motor driver and infrared communication, each of which is electrically connected to the fuel meter 108 mounted on the front surface 101a; and an infrared light-receiving element 120 and an IC (Integrated Circuit) 121 for a stepper motor driver and infrared communication, each of which is electrically connected to the thermometer 111 mounted on the front surface 101a. 
Further, the meter for a vehicle includes a control module 122 attached to the back surface 101b of the display board 101. The control module 122 is provided with an IC 124 (including an I/F (interface) circuit IC, microcomputer IC and infrared communication IC) and an infrared light-emitting element 125 on a board provided with a circuit pattern (not shown in the figure).
The control module 122 is detachably attached to the display board 101 with two fittings 123. The fitting 123 has a groove 123a for fitting the control module board 122 thereinto at one end thereof and four claw-shaped engaging parts 123b for resiliently engaging with corresponding engaging holes 101c of the display board 101 at the opposite end thereof.
Each measured quantity of the vehicle speed, number of revolutions of the engine, amount of the fuel and temperature in the vehicle detected by the respective sensors (not shown in the figure) are inputted into the control module 122 in a form of, for example, serial data. Then, each measured quantity is processed on the basis of the inputted data and then, each measured quantity as the quantity data labeled with a specific identification code is transmitted from the infrared light-emitting element 125 as an infrared signal.
The infrared signal transmitted from the infrared light-emitting element 125 is received by the respective infrared light-receiving elements 114, 116, 118 and 120 and supplied to the respective IC 115, 117, 119 and 121 for a stepper motor driver and infrared communication. Each of the IC 115, 117, 119 and 121 for a stepper motor driver and infrared communication selectively supplies the corresponding measured quantity data of the vehicle speed, number of revolution of the engine, amount of the fuel and temperature in the vehicle to the corresponding meters, that is, the speed meter 102, tachometer 105, fuel meter 108 and thermometer 111 according to the corresponding specific identification code.
Thus, a control section, which is a basic control part for controlling the respective meters, each indicating the measured quantity as to a state of the vehicle, is made a module as the control module 122, thereby enabling to be commonly used for any meter. The output from the control module 122 is made to be an infrared communication output. On the display board 101, the infrared light-receiving element and the corresponding IC for a stepper motor driver and infrared communication are mounted corresponding to each meter.
Each of the IC 115, 117, 119 and 121 for a stepper motor driver and infrared communication is connected to the corresponding stepper motor 103, 106, 109 and 112, each of which constitutes the corresponding meter device such as the speed meter 102, tachometer 105, fuel meter 108 and thermometer 111. Therefore, each stepper motor can be operable with the infrared signal from the control module 122.
Thus, as for the meter for a vehicle shown in FIGS. 15 and 16, a structure of an integrated board is illustrated, on which integrated board each stepper motor 103, 106, 109 and 112 as the movement and each IC 115, 117, 119 and 121 for a stepper motor driver and infrared communication are mounted.
However, as for the meter for a vehicle shown in FIGS. 13 and 14, since each of the casing 12 and board assembly 13 is molded to have a predetermined shape with resin or the like as a separate part separated from the dial 2, therefore if the arrangement of the meter varies depending on a type of the vehicle, it is necessary to make separately the dial, casing and board assembly by changing their shapes depending on a type of the vehicle so as to fit to the arrangement of the meter, causing a problem that such a meter for a vehicle cannot be commonly used for various types of the vehicle. Moreover, since a meter control circuit and so on must be designed and manufactured separately depending on a type of the vehicle, therefore electronic components for constituting the meter control circuit, which components vary depending on a type of the vehicle, must be mounted on the board assembly 13. Once the board assembly 13 is determined, there is a problem that it is difficult to change a specification of the meter control circuit afterward.
Further, the integrated board for the meter for a vehicle shown in FIGS. 13-16 has restriction for designing due to a limited wiring space. Further, a board having high mounting density must be designed separately depending on a combination or layout of the respective meters, causing a necessity of a large man-hour for designing. Further, when the board is completed, there is a problem that an evaluation of noise and so on must be carried out each time.
Further, the integrated board described above needs a mounting space for mounting a plurality of drive elements for carrying out the respective functions of the meter for a vehicle. Further, when the integrated board is designed as a board which can be used in common for a plurality of types of vehicle, there is a problem that a useless mounting space for a drive element for an unnecessary function occurs depending on a type of the vehicle.
It is certainly possible to mount a microcomputer having a CPU for carrying out the functions of a plurality of drive elements on the integrated board. However, in such a case, depending on a type of the vehicle, there is a problem that a driver element, which is not used, exists in the CPU.
It is therefore an objective of the present invention to solve the above problems and to provide a dial module, process for manufacturing the dial module, and a meter employing the dial module, which dial module enables further modularity (further module structure) and common use for a plurality types of vehicle.
It is another objective of the present invention to solve the above problems and to provide a LED display element having a novel constitution suitable for use of the dial module and a meter employing the LED display element.
It is a further objective of the present invention to solve the above problems and to provide a display module and a meter employing the display module, which display module enables further modularity and common use for a plurality types of vehicle.
It is a further objective of the present invention to solve the above problems and to provide a movement module and a meter employing the movement module, which movement module enables further modularity and common use for a plurality types of vehicle.
It is a further objective of the present invention to solve the above problems and to provide a connector module and a meter employing the connector module, which connector module enables further modularity and common use for a plurality types of vehicle.